QoS
QoS Models
best effort
Integrated Services (IntServ)
Differentiated Services (DiffServ)
Mechanisms
classification
marking
policing
shaping
Why?
Lack of bandwidth
Latency and jitter
Packet loss
Increase the link bandwidth capacity
policing and queueing to prioritize traffic according to level of importance
the time it takes for packets from a source to a destination
400 ms should not be exceeded
real-time traffic should be less than 150 ms
Increase link speed
Implement QoS
traffic policing to drop low-priority
traffic shaping to delay packets instead of dropping
not recommended for real-time traffic
can cause jitter
used for traffic that does not require any special treatment.
make a bandwidth reservation and to indicate that they require special QoS treatment
network identifies classes that require special QoS treatment.
for real-time applications such as voice and video
Resource Reservation Protocol (RSVP):
Used to reserve resources throughout a network
Provides call admission control (CAC)
no other IP traffic can use
Any bandwidth reserved and not used is wasted
requires all nodes, including the endpoints support, build, and maintain RSVP path state for every single flow.
does not scale well on large networks
have thousands or millions of flows due to the large number of RSVP to be maintained
start by RSVP PATH messages
receiver source address
destination address
bandwidth to reserve
stored in the RSVP path state of each node
no need signaling protocol
highly scalable since no RSVP flow state to maintain
as bandwidth and delay are managed on a hop-by-hop
divides IP traffic into classes and marks it
Each of the classes can be assigned a different level of service
Layer 7 Classification
Next Generation Network-Based Application Recognition (NBAR2)
Protocol Discovery enables discover and get real-time statistics on applications currently running
Modular QoS CLI (MQC) traffic matching a specific network protocol be placed into one traffic class
different QoS policies can be applied to the different classes of traffic.
QoS mechanism that colors a packet by changing a field within a packet or a frame header with a traffic descriptor